Computer systems generally utilize auxiliary memory storage devices having media on which data can be written and from which data can be read for later use. A direct access storage device (disk drive) incorporating rotating magnetic disks is commonly used for storing data in magnetic form on the disk surfaces. Data is recorded on concentric, radially spaced tracks on the disk surfaces. Magnetic heads are then used to read data from the tracks on the disk surfaces.
FIG. 1 illustrates a prior art MR head, which may be employed as a magnetic head on a slider. The head 30B has a pole tip region 49, an insulation stack region and a coil region, the pole tip region 49 extending from the ABS 47 to the insulation stack region, the insulation stack region extending from the pole tip region 49 to the back gap (not shown) and the coil region located in the insulation stack region but spaced from the pole tip region 49. In the present framework, the first and second shield layers S1 and S2 are located in the pole tip region 49 for the protection of the MR sensor. The first shield S1 terminates between the pole tip region 49 and the coil region along a slope 50. This provides a sunken or depressed area 51 for subsequent thin film layers of the head which makeup the insulation stack. The second gap layer G2 extends along the slope 50 of the first shield S1, thence perpendicular to the ABS 47 toward a back region of the head. It should be noted that leads are not shown following the same path. The leads for the head 30B may take a different path.
The layer S2/P1, write gap, insulation layer I1, write coil, insulation layers I2 and I3, and the second pole piece P2 are all recessed by the depression provided by the first shield layer S1 in the insulation stack region lowering the height of the second pole piece P2 above the write gap plane so as to enhance planarization of the second pole tip PT2 33. This significantly increases the lithographic process window needed for the fabrication of the pole tip PT2. A thinner resist layer permits a narrower pole tip to be precisely constructed with good definition, thereby enhancing the bit density of the head.
The slope 50 of the first shield S1 may be constructed by a resist layer with a negative slope. Permalloy may then be plated adjacent the negative slope, after which the resist is removed to produce the slope 50 of the first shield S1.
To further generalize the structure of the MR head, the ferromagnetic layers that are S2/P1 may be separate layers. In addition, different layers in the head may be planarized [e.g. via chemical mechanical polishing or (CMP)] to increase a fabrication process window for the various parts of the head.
In the case where the write head was a perpendicular write head, one pole tip (e.g. PT2 33) would have a much smaller cross-section at the ABS 47 plane compared to the other pole tip (e.g. PT1 31). The write gap 37 may also vary.
FIGS. 2A-2B illustrate a method of manufacturing the pole tip structure associated with a magnetic head, such as that shown in FIG. 1. See second pole piece P2 of FIG. 1, for example.
FIG. 2A illustrates a cross-sectional view of an initial stack 200 with which a prior art pole tip structure may be manufactured. As shown, the stack 200 includes a first layer 202 which may include AlOx or some other non-magnetic material. Deposited above the first layer 202 is a second layer 204 including, for example, NiFe or a material which substantially consists of a ferromagnetic material. A masking third layer 206 is deposited above the second layer 204. The third layer 206 may include a masked photoresist which is used to define a pole tip structure as will soon become apparent.
FIG. 2B illustrates another cross-sectional view of the stack 200 of FIG. 2 after various processes. In particular, the second layer 204 and a portion of the first layer 202 may be removed utilizing an ion milling process. As a result of the foregoing process, a pole tip structure 210 is defined with a pair of cavities flanking the same. Thereafter, additional AlOx material 208 or similar material is used to fill the cavities.
It is often advantageous to have a pole tip structure 210 with beveled edges such as that shown in FIG. 2B. It is also desirable to generate a pole tip structure that is rectangular with a low aspect ratio or similar height to width ratio as viewed at the cross-section at the ABS 47 plane. Moreover, it is desirable that a top edge of the pole tip structure 210 be planar in nature. Unfortunately, the top edge of the pole tip structure 210 may lose its planarity and exhibit a rounding effect (see 212 of FIG. 2B) as a result of subsequent processes unless specific process steps are taken to maintain pole definition and function.